The efficient operation of many optical devices requires very accurate alignment of various components. In semiconductor laser transmitters, for example, a misalignment of perhaps a fraction of micron between the semiconductor diode and an optical fiber can reduce transmitter efficiency by fifty percent or more. There is also a need for very accurate alignment of optical fiber with other optical components such as photosensitive transducers and waveguides.
Many known methods for achieving accurate alignment have been proposed but each method has undesirable limitations or costs. Some of the known methods use solder to fix optical fiber onto various substrates to secure an aligned relationship. Unfortunately, many of these methods require heating the components to such a high temperature that the semiconductor laser can no longer be operated safely. Since alignment tolerances are so critical, laser operation is essential to determine proper alignment.
One known method, such as that disclosed in U.S. Pat. No. 5,307,434, for example, overcomes this problem by fixing the optical fiber onto a layered structure that is insulated from the base supporting the laser; however, this solution is undesirable because of the costs required to form the insulating structure.
Many known methods that use solder and resins are also unattractive because the position of the optical fiber shifts as the solder cools or the resins cure, thereby moving the optical fiber out of optimum alignment.